The current state of the art in solid rocket motor (SRM) insulation is an EPDM rubber with a filler of Kevlar fibers or silica. The disadvantage of these systems include the inability to process the material after the final curing as well as increased difficulty in processing these materials with an incompatible filler on the size scale of Kevlar™ fibers or fumed silica. Also these formulations cannot be successfully sprayed onto a motor case.
Conventional carbon fibers (5-10 microns in diameter) have been looked into to replace Kevlar™ in SRM insulation with good results. A drawback of this technology is the use of exotic extrusion techniques in order to maintain the original aspect ratio of the carbon fibers. The use of Vapor Grown Carbon Fiber has also been described as a filler in EPDM systems, but it too suffers from the same post processing issues as the EPDM/Kevlar and cannot be sprayed.
Accordingly, there is need and market for SRM insulation that overcomes the above prior art shortcomings.
There has now been discovered an SRM insulation that has ease of processing, can be applied by advanced spraying techniques and has improved durability, as described below.